1. Technical Field
The embodiments herein generally relate to steam turbines and particularly relates to an arrangement of the turbine stages in a steam turbine for saturated steam applications. The embodiments herein more particularly relates to a method and a system for removal of condensate from steam turbines and a system for preventing cascading blade failures.
2. Description of the Related Art
Turbines are rotating machines which convert the energy contained in a working fluid to useful work. In general, a turbine comprises a shaft and a circular disk or a ring. The circumference of the circular disk comprises a series of blades. The series of blades are shaped and aligned based on the rotational speed of the turbine, energy in the fluid and application. There are numerous types of turbines depending on the type of input, such as steam, water, wind, gas, etc.
The steam turbines generally have one or more stages, but multiple stage turbines are also well known for utilizing the working fluid, such as steam, more effectively. The multiple stage turbines are generally the axial steam turbines in which a series of rotors or disks are aligned onto the same rotating shaft one after the other. Steam in superheated state, which is the steam heated beyond a saturation temperature, is preferred for use in the steam turbines. But the steam in saturated state is used widely across the industries. The steam is produced when the water is heated. When all the water has changed phase to steam, the steam is said to be ‘saturated’. When the saturated steam is further heated, a superheated steam is produced. The saturated steam offers an easy and controlled operation and hence is widely preferred by the industries for use in the processes.
The reason for not using the saturated steam in all the industries is mainly due to the characteristics of the saturated steam. The saturated steam is in a vapor phase which is just above the water/liquid phase. When the saturated steam is passed from one stage to another stage, a part of the steam is condensed and the water droplets are formed due to an expansion of the saturated steam. The jet of water droplets is accelerated through the nozzle and the jet of water droplets hits the blades of the rotor disk at very high speed and creates pitting on them. If the rotor disk is continued to operate in such conditions, the blades are likely to fail. Further, in case of an axial multistage turbine disk arrangement, the water droplets are carried over to all the stages to deteriorate the condition of the blades at each stage. The existing methods and arrangements do not provide a solution for safeguarding the multistage turbines against such damage.
Also in the event of a blade failure, where the turbine blade or a part of the blade breaks away from the turbine disk, the projectiles are bound to strike the subsequent stages causing a catastrophic failure. For the steam turbines with four or fewer stages, this method provides an alternative arrangement in which each turbine stage is isolated from the other to prevent a cascading blade failure.
Hence there is need for a system and a method to arrange the multiple stages of a steam turbine for the saturated steam applications. Also, there is a need for a system and a method to arrange the multiple stages of steam turbine to prevent a deterioration of the steam turbine in the saturated steam applications. Further, there is a need for a method and a system for facilitating the multiple extractions and injections in the steam turbines. Still further there is a need for an arrangement of the multiple stages to prevent a cascading blade failure in the steam turbines.
The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.